1. Field of the Invention
The present invention relates generally to methods and apparatus for orthopedic joint repair and reconstruction, and more particularly to a novel set of surgical instruments and a method of using the same for the preparation and implantation of osteochondral allografts for resurfacing of the hip joint, knee joint, and shoulder joint. The grafts are prepared to a uniform shape and peripheral topography to the topography of the recipient site.
2. Discussion of Related Art Including Information Disclosed Under 37 CFR §§1.97, 1.98
Reconstruction of joints remains an ongoing area of investigation. Since the work of Erich Lexer in the early part of the twentieth century, entire joints have been transplanted into human patients. These large grafts termed “allografts” were associated with high failure rates and cartilage degeneration. Additionally, the transplant recipient was required to immobilize the joint and to avoid bearing weight on the transplant for long periods of time.
In the early 1970's, the concept of shell allografts consisting of fresh bone and cartilage was introduced. With these grafts, only a thin shell of bone was transplanted. The thin bone shell essentially functioned as a carrying vehicle for the fresh articular cartilage that would remain populated with cells from the donor. Once the bone of the host healed to the graft bone, the articular cartilage would continue to receive nutrition from the synovial fluid in the joint. The bone, due to its small volume, generated a minimal immune response. Using this technique, large areas of articular cartilage could be repaired with normal cartilage with no need for systemic immunosuppressive medications. The success of this surgical procedure is well documented and is based on both clinical improvements as well as documented long-term donor cell viability (nearly 30 years after the transplantation).
Tissue engineering can be defined as a multidisciplinary field applying the principles of engineering and biological sciences with the goal of regeneration and/or restoration of tissues and organs. Up to the present time the major areas of clinical application of tissue engineering in orthopaedic surgery have been in autologous chondrocyte implantation, in which cells from a donor cartilage are pre-harvested, cultured, and then injected into the recipient under a periosteal or synthetic patch with the aim of forming mature hyaline-like cartilage. The principal efforts in this field are now being directed at manufacturing complete tissues that include both cartilaginous and osseous components of the joint surface in order to optimize healing of the artificial tissue to the recipient bone. However, to date no osteochondral tissue engineered constructs for cartilage repair have been widely used in humans. Were such an implant to be developed, a method will be required to prepare the recipient site precisely based on its surface characteristics so as to accommodate the implant with a flush joint surface.
In the area of osteochondral allograft instrumentation, the emphasis has been on cylindrical instrumentation to prepare cores that can be trimmed and transplanted into cylindrically prepared recipient sites in the complementary portion of the joint. In U.S. Pat. No. 6,488,033, to Cerundolo, there is described a method of obtaining and placing an osteochondral allograft in substantially the same orientation as the damaged segment of the bone which is initially removed from the patient. With this technique, the surface of the transplanted plug is matched to the contour of the excised osteochondral tissue. However, the placement of the guides is essentially dependent on free hand techniques and the guides do not provide a precise match with the complex contours of the cartilaginous surface.
U.S. Pat. No. 6,591,581, to Schmieding, teaches a method and instrumentation for the preparation, distribution, and insertion of round, size specific osteochondral allografts. The distribution network for fresh osteochondral allograft cores is laid out, along with some details for instrumentation in preparing such osteochondral plugs and recipient sites. This instrumentation is analogous to that discussed in U.S. Pat. No. 5,919,196, to Bobic et al, for autologous osteochondral transfer, otherwise known as mosaicplasty. However, no insights are offered by these publications into meeting the challenges of preparing a perfect surface match for these large osteochondral cylindrical grafts.